The liquid crystal display device generally includes an array substrate, a counter substrate and a liquid crystal layer held therebetween. The array substrate and the counter substrate respectively equipped with electrodes are formed of a pair of glasses, and attached by a seal material in a peripheral area.
In a color active-matrix type liquid crystal display device, for example, the array substrate includes switching elements such as thin film transistors (TFT) formed of poly-silicon, pixel electrodes, signal lines, gate lines connected with the switching element. The counter substrate includes a counter electrode and a color filter. The array substrate and the counter substrate are attached by the seal material arranged in a peripheral area. In the color active-matrix type liquid crystal display device, respective polarizer plates are attached on both outer surfaces of the array substrate and the counter substrate. Color images are displayed by switching the switching element.
A shield layer is provided between color filters colors in different colors each other in a peripheral area. The color filters run on the shield layer to prevent generation of a light leak resulting from patterning accuracy.
Conventionally, a method in which plastic beads with uniform particle diameter are scattered between the substrates is used as a spacer for keeping a cell gap between the two substrates uniform. Recently, a pillar shaped spacer formed on one of the substrates has been used. The method is effective in achieving the uniform cell gap by selectively arranging the spacers and raising accuracy of a spacer height. The method of pasting two substrates together is also important for achieving the uniform gap.
There are two types of forming the liquid crystal layer and attaching the pair of substrates by the seal material. The first method uses an injecting hole formed in the seal material arranged in the peripheral area of the array substrate. After attaching the substrates in a vacuum condition, the gap is formed by applying pressure to the substrates. The second method is called One Drop Fill (ODF) method. After attaching the substrates in the vacuum condition in a state in which a predetermined amount of liquid crystal material was dropped in a region surrounded with the seal material on the array substrate, the state is changed from the vacuum condition to an atmosphere condition. The seal material is crushed by a pressure difference between the inside pressure of the cell gap and outside pressure, thereby a predetermined cell gap is formed. Since the ODF method has advantages such as shorten of tact time, effective use of materials and high gap accuracy, the ODF method is widely used for forming the liquid crystal layer.
Generally, in the ODF method, spacers are arranged in the seal material. Thereby, when the vacuum state is turned to the atmosphere pressure state, excessive crushing of the seal material can be prevented, and a cell gap distortion in the display area can be controlled.
A display defect is resulted when variations in the dropped amount of the liquid crystal materials and cell volume exist, and when the volume of the liquid crystal materials is excess or too little. Especially, in case the amount of the liquid crystal material is excess, the display defect corresponding to the cell form is generated at the time of pasting the array substrate and the counter substrate together.
For example, if the cell gap in the seal material is sufficiently large with respect to the display area, a cross-sectional view of the cell becomes a hard drum form. In case the amount of the liquid crystal materials is excess, since the liquid crystal materials are more stored in the region where the cell gap is larger, the region in which the cell gap is larger is sighted as an unevenness gap in the circumference. That is, the circumference in the display area colors yellow. On the other hand, when the seal material is crushed and becomes thin, the cell becomes a paunch form. In case the liquid crystal materials are excessive, the liquid crystal materials are more stored in the display area, and the stored region is sighted as unevenness. Even when the amount of the liquid crystal materials is slightly excessive, if the cell is stood while being warmed in a manufacturing process, the liquid crystal materials in a central portion move to a lower side and stored there by its own weight, and the circumference of the lower side is sighted as unevenness (gravity unevenness).
In order to raise adhesiveness of the seal material between the seal material and the array substrate, it is necessary to remove a portion of an under-resin film formed on the array substrate so that a predetermined area is secured, in which the seal material directly contacts with a non-organic film such as a silicon-oxide.
Moreover, there is a tendency that a seal material arrangement region is made narrow as the demand for making a narrow frame becomes strong. Accordingly, if the predetermined area is secured to contact the seal material with the non-organic film, a restriction arises in the spacer arrangement in the seal material.
Moreover, the spacer in the seal material is simultaneously formed with the spacer which forms the cell gap between the array substrate and the counter substrate in the display area. Accordingly, when the spacer in the seal material is formed in a pattern end of an under-resin film used as a base, there is a tendency that the height of the spacer in the seal material becomes lower compared with the spacer in the display area by leveling phenomenon.
The spacer height formed in the pattern end of the under-resin film is dependent on the removed area of the under-resin film. The under-resin film in a mounting portion for mounting ICs on the array substrate is also removed. Accordingly, the total removed area of the under-resin film between peripheral areas of adjacent display panels becomes large if the mounting portion is provide between the peripheral areas of the adjacent display panels comparing with the peripheral areas not adjacent to the mounting portion. As a result, the height of the spacer formed in the pattern end of the under-resin film adjacent to the mounting portion becomes lower comparing with that of the spacer arranged in the peripheral area not adjacent to the mounting portion. As a result, the spacer height in the seal material adjacent to the mounting portion tends to become remarkably lower comparing with the height of the spacer in the display area.
In the manufacturing process, when the display panel is vertically put by turning the mounting portion on a down side, display unevenness may be resulted while being warmed in the manufacturing process.